From Metabolism to Polymorphism in Bacterial Populations: A Theoretical Study

Abstract

Abstract. Stable polymorphisms are commonly observed in experimental bacterial populations grown in homogeneous media. Evidence is accumulating that metabolic interactions might be the main mechanism underlying the emergence and maintenance of such polymorphisms. To date, however, attempts to model the evolution of bacterial polymorphism have not considered metabolism as a possible component of polymorphism maintenance. Here, we propose a simulation approach to model the evolution of selected polymorphisms in a bacterial population. Using recent knowledge of the relationship between bacterial fitness and metabolism, we build a simple metabolic model and test the effect of resource competition on polymorphism. Without making an a priori hypothesis on fitness functions, we show that stable polymorphic situations could be observed under high nutrient competition, and we propose a functional, metabolismbased explanation to the debated issue of polymorphism maintenance.

The Classification and Evolution of Bacterial Cross-Feeding

“…We define metabolic cross-feeding as an interaction between bacterial strains in which molecules resulting from the metabolism of one strain are further metabolised by another strain. In general, the term "metabolic cross-feeding" is used according to this definition, though not further sub-divided according to characteristics of the relationship, as we shall here (Porcher et al, 2001;Doebeli, 2002;Duncan et al, 2002;Belenguer et al, 2006Belenguer et al, , 2008MacLean et al, 2010;Egan et al, 2014;Rivière et al, 2015;Pacheco et al, 2019). Closely related to cross-feeding is the term "syntrophy, " which has been defined as "obligately mutualistic metabolism" (Morris et al, 2013).…”

Divergence and Redundancy of Transport and Metabolic Rate-Yield Strategies in a SingleEscherichia coliPopulation

“…Investigation of metabolic adaptation in simple environments limited by a single resource has been limited to a small number of isolates from long-term cultures, like nutrient-limited chemostat cultures (39,47). Long-term coexistence of phenotypically distinct clones has been demonstrated (10,39,40), and metabolic variance has been described for the creation of cross-feeding consortia partitioning metabolism in a longterm experimental population (36,43). In general, population heterogeneity determined through phenotypic characterization was found in other studies of experimental evolution with E. coli (15,18,32,34,42).…”